PASTEURELLA 3EPTICA 781 



Biochemical. — Acid, no gas, in glucose, maltose, mannitol, salicin, arabinose, xylose, and 

 sometimes rhamnose and glycerol within 14 days. L.M. unaltered or turned slightly 

 acid ; Indole — ; M.R. + ; V.P. — ; Nitrates + ; NH3 -f ; Methylene blue 

 reduction — ; HgS very sUght -{- ; Catalase -J — |-. 



Antigenic Structure. — Appears to possess a heat-labile envelope antigen and a heat-stable 

 somatic antigen. The somatic antigen is similar to one of the somatic antigens in 

 Past, pseudotuberculosis. Immune sera with protective and curative properties for 

 animals can be prepared by injection of horses with living or dead baciUi. 



Pathogenicity. — No true exotoxin formed. Virulence subject to considerable variation. 

 Causes plague in man and rodents. Experimental inoculation reproduces disease 

 in mice, rats, guinea-pigs, rabbits, marmots, ground squirrels, and other rodents ; 

 also in monkeys. Dogs, cats, pigs, cattle, sheep, goats, and horses are difficult to 

 infect. Birds, with exception of sparrows, are completely resistant. 



Subcutaneous inoculation of a 24-hours' broth culture into a mouse or guinea- 

 pig is fatal in 2 to 5 days. P.M. necrotic local lesion surrounded by congestion 

 and oedema. Regional glands enlarged and embedded in bloody oedema ; they are 

 soft and necrotic on section. Spleen firm, slightly enlarged and congested ; may 

 contain mihary, soft, grey nodules ; liver peppered with tiny necrotic foci. Micro- 

 scopically, bacilli found in abundance in local lesion and bubo ; smaller numbers 

 in spleen and heart's blood. 



Pasteurella septica 



Isolation. — First member of the Pasteurella group isolated by Kitt in 1878. Past- 

 aviseptica isolated by Pasteur in 1880. 



Habitat. — Parasites of domestic and wild animals and birds. 



Morphology. — Very small, 0-7-2 /j. X 0-3-0-6 ft, ovoid bacilli, with straight axis, shghtly 

 convex sides, and rounded ends ; arranged singly, in pairs, or in small bundles. 

 In smears from the animal body the organisms are regular, ovoid, and evenly 

 distributed ; on agar cultures they are more rod-shaped and often show pleo- 

 morphism. Non-motile, non-sporing. May form a capsule m animal body, and 

 an envelope in artificial media. Shows bipolar staining. Gram-negative and non- 

 acid-fast. 



Agar Plate. — 24 hours at 31° C. Round, 0-5-1 -0 mm. in diameter, low convex, amor- 

 phous, greyish-yellow, translucent colonies, with smooth, glistening surface and 

 entire edge ; consistency butyrous ; emulsifiabiUty easy. 



5 days at 37° C. Up to 6 mm. in diameter, differentiated into a brownish, finely 

 granular, sometimes ringed or striated, nearly opaque centre and a clearer, smooth, 

 homogeneous, greyish-yellow translucent periphery. 



Deep Agar Shake. — 5 days at 37° C. Thick surface growth ; numerous, punctiform, un- 

 differentiated colonies scattered throughout medium. 



Agar Stroke. — 24 hours at 37° C. Moderate, confluent, raised, greyish-yellow, trans- 

 lucent growth, with ghstening, wavy or beaten-copper surface and finely lobate 

 edge. 



Gelatin Stab. — 7 days at 22° C Good, filiform growth, confluent at top, discrete below, 

 extending to bottom ; raised surface growth, 5 mm. in diameter, with crenated 

 edge, no Uquefaction. 



Broth. — 24 hours at 37° C. Moderate growth with sUght turbidity, and a slight powdery 

 or viscous deposit. Later the turbidity increases, and a heavy, viscous deposit 

 forms, disintegrating partly on shaking but leaving irregularly-sized wisp-like 

 masses of growth in suspension. An incomplete surface pellicle forms with an 

 inconspicuous ring growth. 



Loeffler's Serum. — 24 hours at 37° C. Good confluent growth, similar to that on agar. 



